From patchwork Tue Aug 8 16:19:05 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Caron X-Patchwork-Id: 711872 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6361CC001B0 for ; Tue, 8 Aug 2023 18:49:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229877AbjHHStO (ORCPT ); Tue, 8 Aug 2023 14:49:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232311AbjHHSs4 (ORCPT ); Tue, 8 Aug 2023 14:48:56 -0400 Received: from mx07-00178001.pphosted.com (mx08-00178001.pphosted.com [91.207.212.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 242556E8A; Tue, 8 Aug 2023 10:01:12 -0700 (PDT) Received: from pps.filterd (m0046661.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.17.1.22/8.17.1.22) with ESMTP id 378Co0O9026039; Tue, 8 Aug 2023 18:20:42 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding:content-type; s= selector1; bh=K5Mf4K28dVqGgOXG/25wlgXtHIWlnOLbNeyiTKRCs58=; b=cH c2NK+6YnqFiDsk2HXFA6x2aBJ/xb+dEOYYd659NMHHF9bKikC8HLw4lB+jcdy3IJ qIEfj3Y0KBpuMznqAmxJGJsQRrQBnaXxvbmZTbEWyoovliSpuWav5w6w8P6igPYA PWWK2S+XLj+f92LQ4dbbewn/VCGh44CiJeo+NgaXvBREqr+UW9vyyEotMo90vcjP i8mqgow4EmIqhe7ecmPaYP2WQudpUvy0ORWvzWXHMtLmGg6MwDx5+/UgiKMfCKtI WDuhzrQ8R39UG380fdHbBjw3lpNKMW+lg2MUIdXlO4gGGN6yHsz5dp8x5J9v99A7 ZEFy7ltNddT9PvBn+4Sw== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3sbp2d95fg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 08 Aug 2023 18:20:42 +0200 (MEST) Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id B5541100061; Tue, 8 Aug 2023 18:20:41 +0200 (CEST) Received: from Webmail-eu.st.com (eqndag1node4.st.com [10.75.129.133]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id ABADB236928; Tue, 8 Aug 2023 18:20:41 +0200 (CEST) Received: from localhost (10.201.20.168) by EQNDAG1NODE4.st.com (10.75.129.133) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Tue, 8 Aug 2023 18:20:41 +0200 From: Valentin Caron To: Greg Kroah-Hartman CC: Jiri Slaby , Alexandre Torgue , Amelie Delaunay , , , , , Valentin Caron Subject: [PATCH v2 5/6] serial: stm32: replace access to DMAR bit by dmaengine_pause/resume Date: Tue, 8 Aug 2023 18:19:05 +0200 Message-ID: <20230808161906.178996-6-valentin.caron@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230808161906.178996-1-valentin.caron@foss.st.com> References: <20230808161906.178996-1-valentin.caron@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.201.20.168] X-ClientProxiedBy: EQNCAS1NODE3.st.com (10.75.129.80) To EQNDAG1NODE4.st.com (10.75.129.133) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-08-08_15,2023-08-08_01,2023-05-22_02 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org It's rather advised to rely on DMA pause / resume instead of clearing/setting DMA request enable bit for the same purpose. Some DMA request/acknowledge race may encountered by doing so. We prefer to use dmaengine_pause and resume instead to pause a dma transfer when it is necessary. Create two new functions (stm32_usart_rx_dma_pause, stm32_usart_rx_dma _resume) to handle dma error when pausing/resuming. And rename stm32_usart_start_rx_dma_cyclic() to stm32_usart_rx_dma_start_or_resume() and use this function to resume an rx dma transfer. If resume fail, stm32_usart_rx_dma_start_or_resume can create a new transfer to continue. It is also safer to close DMA before reset DMAR in stm32_usart_shutdown. Signed-off-by: Valentin Caron --- drivers/tty/serial/stm32-usart.c | 200 ++++++++++++++++--------------- 1 file changed, 106 insertions(+), 94 deletions(-) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 0dae05a7abe6..8fc0526be898 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -326,6 +326,22 @@ static int stm32_usart_dma_pause_resume(struct stm32_port *stm32_port, return ret; } +static int stm32_usart_rx_dma_pause(struct stm32_port *stm32_port) +{ + return stm32_usart_dma_pause_resume(stm32_port, stm32_port->rx_ch, + DMA_IN_PROGRESS, dmaengine_pause, + stm32_usart_rx_dma_started, + stm32_usart_rx_dma_terminate); +} + +static int stm32_usart_rx_dma_resume(struct stm32_port *stm32_port) +{ + return stm32_usart_dma_pause_resume(stm32_port, stm32_port->rx_ch, + DMA_PAUSED, dmaengine_resume, + stm32_usart_rx_dma_started, + stm32_usart_rx_dma_terminate); +} + /* Return true when data is pending (in pio mode), and false when no data is pending. */ static bool stm32_usart_pending_rx_pio(struct uart_port *port, u32 *sr) { @@ -485,7 +501,8 @@ static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force rx_dma_status = dmaengine_tx_status(stm32_port->rx_ch, stm32_port->rx_ch->cookie, &stm32_port->rx_dma_state); - if (rx_dma_status == DMA_IN_PROGRESS) { + if (rx_dma_status == DMA_IN_PROGRESS || + rx_dma_status == DMA_PAUSED) { /* Empty DMA buffer */ size = stm32_usart_receive_chars_dma(port); sr = readl_relaxed(port->membase + ofs->isr); @@ -502,7 +519,6 @@ static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force } else { /* Disable RX DMA */ stm32_usart_rx_dma_terminate(stm32_port); - stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR); /* Fall back to interrupt mode */ dev_dbg(port->dev, "DMA error, fallback to irq mode\n"); size = stm32_usart_receive_chars_pio(port); @@ -514,6 +530,76 @@ static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force return size; } +static void stm32_usart_rx_dma_complete(void *arg) +{ + struct uart_port *port = arg; + struct tty_port *tport = &port->state->port; + unsigned int size; + unsigned long flags; + + spin_lock_irqsave(&port->lock, flags); + size = stm32_usart_receive_chars(port, false); + uart_unlock_and_check_sysrq_irqrestore(port, flags); + if (size) + tty_flip_buffer_push(tport); +} + +static int stm32_usart_rx_dma_start_or_resume(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct dma_async_tx_descriptor *desc; + enum dma_status rx_dma_status; + int ret; + + if (stm32_port->throttled) + return 0; + + if (stm32_port->rx_dma_busy) { + rx_dma_status = dmaengine_tx_status(stm32_port->rx_ch, + stm32_port->rx_ch->cookie, + NULL); + if (rx_dma_status == DMA_IN_PROGRESS) + return 0; + + if (rx_dma_status == DMA_PAUSED && !stm32_usart_rx_dma_resume(stm32_port)) + return 0; + + dev_err(port->dev, "DMA failed : status error.\n"); + stm32_usart_rx_dma_terminate(stm32_port); + } + + stm32_port->rx_dma_busy = true; + + stm32_port->last_res = RX_BUF_L; + /* Prepare a DMA cyclic transaction */ + desc = dmaengine_prep_dma_cyclic(stm32_port->rx_ch, + stm32_port->rx_dma_buf, + RX_BUF_L, RX_BUF_P, + DMA_DEV_TO_MEM, + DMA_PREP_INTERRUPT); + if (!desc) { + dev_err(port->dev, "rx dma prep cyclic failed\n"); + stm32_port->rx_dma_busy = false; + return -ENODEV; + } + + desc->callback = stm32_usart_rx_dma_complete; + desc->callback_param = port; + + /* Push current DMA transaction in the pending queue */ + ret = dma_submit_error(dmaengine_submit(desc)); + if (ret) { + dmaengine_terminate_sync(stm32_port->rx_ch); + stm32_port->rx_dma_busy = false; + return ret; + } + + /* Issue pending DMA requests */ + dma_async_issue_pending(stm32_port->rx_ch); + + return 0; +} + static void stm32_usart_tx_dma_terminate(struct stm32_port *stm32_port) { dmaengine_terminate_async(stm32_port->tx_ch); @@ -585,20 +671,6 @@ static void stm32_usart_tc_interrupt_enable(struct uart_port *port) stm32_usart_set_bits(port, ofs->cr1, USART_CR1_TCIE); } -static void stm32_usart_rx_dma_complete(void *arg) -{ - struct uart_port *port = arg; - struct tty_port *tport = &port->state->port; - unsigned int size; - unsigned long flags; - - spin_lock_irqsave(&port->lock, flags); - size = stm32_usart_receive_chars(port, false); - uart_unlock_and_check_sysrq_irqrestore(port, flags); - if (size) - tty_flip_buffer_push(tport); -} - static void stm32_usart_tx_interrupt_disable(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); @@ -924,11 +996,10 @@ static void stm32_usart_throttle(struct uart_port *port) spin_lock_irqsave(&port->lock, flags); /* - * Disable DMA request line if enabled, so the RX data gets queued into the FIFO. + * Pause DMA transfer, so the RX data gets queued into the FIFO. * Hardware flow control is triggered when RX FIFO is full. */ - if (stm32_usart_rx_dma_started(stm32_port)) - stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR); + stm32_usart_rx_dma_pause(stm32_port); stm32_usart_clr_bits(port, ofs->cr1, stm32_port->cr1_irq); if (stm32_port->cr3_irq) @@ -950,14 +1021,15 @@ static void stm32_usart_unthrottle(struct uart_port *port) if (stm32_port->cr3_irq) stm32_usart_set_bits(port, ofs->cr3, stm32_port->cr3_irq); + stm32_port->throttled = false; + /* - * Switch back to DMA mode (re-enable DMA request line). + * Switch back to DMA mode (resume DMA). * Hardware flow control is stopped when FIFO is not full any more. */ if (stm32_port->rx_ch) - stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR); + stm32_usart_rx_dma_start_or_resume(port); - stm32_port->throttled = false; spin_unlock_irqrestore(&port->lock, flags); } @@ -968,8 +1040,7 @@ static void stm32_usart_stop_rx(struct uart_port *port) const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; /* Disable DMA request line. */ - if (stm32_port->rx_ch) - stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR); + stm32_usart_rx_dma_pause(stm32_port); stm32_usart_clr_bits(port, ofs->cr1, stm32_port->cr1_irq); if (stm32_port->cr3_irq) @@ -981,64 +1052,6 @@ static void stm32_usart_break_ctl(struct uart_port *port, int break_state) { } -static int stm32_usart_start_rx_dma_cyclic(struct uart_port *port) -{ - struct stm32_port *stm32_port = to_stm32_port(port); - const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - struct dma_async_tx_descriptor *desc; - enum dma_status rx_dma_status; - int ret; - - if (stm32_port->rx_dma_busy) { - rx_dma_status = dmaengine_tx_status(stm32_port->rx_ch, - stm32_port->rx_ch->cookie, - NULL); - if (rx_dma_status == DMA_IN_PROGRESS) - return 0; - - dev_err(port->dev, "DMA failed : status error.\n"); - stm32_usart_rx_dma_terminate(stm32_port); - } - - stm32_port->rx_dma_busy = true; - - stm32_port->last_res = RX_BUF_L; - /* Prepare a DMA cyclic transaction */ - desc = dmaengine_prep_dma_cyclic(stm32_port->rx_ch, - stm32_port->rx_dma_buf, - RX_BUF_L, RX_BUF_P, - DMA_DEV_TO_MEM, - DMA_PREP_INTERRUPT); - if (!desc) { - dev_err(port->dev, "rx dma prep cyclic failed\n"); - stm32_port->rx_dma_busy = false; - return -ENODEV; - } - - desc->callback = stm32_usart_rx_dma_complete; - desc->callback_param = port; - - /* Push current DMA transaction in the pending queue */ - ret = dma_submit_error(dmaengine_submit(desc)); - if (ret) { - dmaengine_terminate_sync(stm32_port->rx_ch); - stm32_port->rx_dma_busy = false; - return ret; - } - - /* Issue pending DMA requests */ - dma_async_issue_pending(stm32_port->rx_ch); - - /* - * DMA request line not re-enabled at resume when port is throttled. - * It will be re-enabled by unthrottle ops. - */ - if (!stm32_port->throttled) - stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR); - - return 0; -} - static int stm32_usart_startup(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); @@ -1064,7 +1077,7 @@ static int stm32_usart_startup(struct uart_port *port) writel_relaxed(USART_RQR_RXFRQ, port->membase + ofs->rqr); if (stm32_port->rx_ch) { - ret = stm32_usart_start_rx_dma_cyclic(port); + ret = stm32_usart_rx_dma_start_or_resume(port); if (ret) { free_irq(port->irq, port); return ret; @@ -1811,11 +1824,6 @@ static int stm32_usart_serial_remove(struct platform_device *pdev) pm_runtime_put_noidle(&pdev->dev); stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_PEIE); - cr3 = readl_relaxed(port->membase + ofs->cr3); - cr3 &= ~USART_CR3_EIE; - cr3 &= ~USART_CR3_DMAR; - cr3 &= ~USART_CR3_DDRE; - writel_relaxed(cr3, port->membase + ofs->cr3); if (stm32_port->tx_ch) { stm32_usart_of_dma_tx_remove(stm32_port, pdev); @@ -1827,7 +1835,12 @@ static int stm32_usart_serial_remove(struct platform_device *pdev) dma_release_channel(stm32_port->rx_ch); } - stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT); + cr3 = readl_relaxed(port->membase + ofs->cr3); + cr3 &= ~USART_CR3_EIE; + cr3 &= ~USART_CR3_DMAR; + cr3 &= ~USART_CR3_DMAT; + cr3 &= ~USART_CR3_DDRE; + writel_relaxed(cr3, port->membase + ofs->cr3); if (stm32_port->wakeup_src) { dev_pm_clear_wake_irq(&pdev->dev); @@ -1999,7 +2012,7 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port, const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; struct tty_port *tport = &port->state->port; int ret; - unsigned int size; + unsigned int size = 0; unsigned long flags; if (!stm32_port->wakeup_src || !tty_port_initialized(tport)) @@ -2021,10 +2034,9 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port, */ if (stm32_port->rx_ch) { spin_lock_irqsave(&port->lock, flags); - /* Avoid race with RX IRQ when DMAR is cleared */ - stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR); /* Poll data from DMA RX buffer if any */ - size = stm32_usart_receive_chars(port, true); + if (!stm32_usart_rx_dma_pause(stm32_port)) + size += stm32_usart_receive_chars(port, true); stm32_usart_rx_dma_terminate(stm32_port); uart_unlock_and_check_sysrq_irqrestore(port, flags); if (size) @@ -2035,7 +2047,7 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port, stm32_usart_receive_chars(port, false); } else { if (stm32_port->rx_ch) { - ret = stm32_usart_start_rx_dma_cyclic(port); + ret = stm32_usart_rx_dma_start_or_resume(port); if (ret) return ret; }